The in-plane crashworthiness of multi-layer regularly arranged circular honeycombs

The in-plane crashworthiness of multi-layer regularly arranged circular honeycombs are investigated numerically at v = 1–250 m/s, with aim to disclose the influences of t/R ratio and crushing velocity, v. A novel evaluation methodology of crashworthiness and a new mechanical term, most appropriate strain, are put forward, which results in some new evaluation parameters. The theoretical analysis shows the most appropriate strain is a significant parameter for measuring the crashworthiness. Different deformation modes cause different change rules of these evaluation parameters. Under the quasi-static homogeneous mode and transition mode, the most appropriate strain is linear with the t/R ratio for a given v; the crushing force efficiency is approximately independent of t/R and sensitive to the v; the maximum energy absorption efficiency roughly decreases and then fluctuates. With the increase of v, the crushing force efficiency first becomes smaller sharply, and then fluctuates. Under dynamic mode, the maximum energy absorption efficiency is nearly constant for a given t/R ratio. Based on the finite element results, the empirical expressions of all evaluation parameters are given. The finite element calculated results of optimal specific energy absorption are consistent with those calculated by empirical expressions, which validates all empirical expressions.